More like we need psychologists to ask "why are companies still working with IBM's efficiencies 30 years after its peak?" The workers don't have to care but the businesses dealing with IBM should.
I may be wrong but I think it's mostly for things like enterprise support in case something goes wrong. IBM has had a large footprint in enterprises (WebSphere MQ, etc). People don't want disruptions in case your own kafka cluster with in-house engineers accountable for everything. So having enterprise support for product/ infra gives a sense of safety. At times rightly so. Depends on a lot of factors- risk appetite, capabilities of in-house engineers, what's at stake, and mostly psychological safety, etc.
